More than 1,300 flights expected to be affected after airport closes down for all of Friday due to a substation fireLive coverage: significant travel disruption expectedLondon’s Heathrow airport will be closed all day on Friday, sparking global travel chaos, after a fire at an electrical substation caused a “significant power outage” there, and left thousands of homes without power.The shutdown occurred just hours before the travel hub – one of the busiest two-runway airports in the world – was due to open, forcing at least 120 flights that were already in the air to divert, according to Flightradar24, with more